Inhibition of Streptococcus mutans Adherence to Pit and Fissure Sealants Containing Powdered Semiconductor TiO₂

Abstract

     We investigated the adherence of S. mutans to pit and fissure sealants containing the powdered semiconductor TiO₂, which exhibits a photocatalytic reaction. TiO₂ (0.5, 1.0 and 5.0%) was dispersed in the sealant which was then polymerized and illuminated with a fluorescent Iamb (peak wavelength at 578 nm, band width 202 nm) at 2,000 lux for 120 min in saline solution. Three strains of S. mutans (Ingbritt, NCTC 10449 and GS-5) were incubated at 37℃ for 48 hr in an aerobic growth chamber. The viability of S. mutans on the TiO₂-containing sealant varied with the bacterial strain. Scanning electron microscopy showed that TiO₂ had an anti-bacterial effect. This effect, especially the surface adherence to the sealant containing TiO₂, was different for the various strains. Ingbritt and NCTC 10449 demonstrated polysaccharide-like substances, while GS-5 showed aggregation of the bacterial cells. Brinell hardness number slightly increased, but flextural strength decreased with addition of TiO₂ in the sealant.
     It seems that the photocatalytic reaction of TiO₂ in the sealant inhibits S. mutans adherence.